ST. LOUIS — The top weather story today continues to be the heat. Highs will be near record levels in the upper 90s to lower-100s. The top heat index will reach as high as 105-110 today.
The extreme heat may help to bubble up a couple of isolated storms late this afternoon into the night. The initial development is most likely to be well north of metropolitan St. Louis. However, I am a little concerned that the urban heat island may create a hot spot of sorts near the city of St. Louis resulting in a small cluster of storms near downtown late in the day. This is a low-probability event, but it is worth keeping a watch on it. Any isolated evening storms would be capable of brief downburst winds as they collapse.
Isolated evening storms are expected to send an outflow boundary south through the region overnight. This outflow may be strong enough to focus additional isolated to scattered storms along its track from north to south. This means a chance for thunderstorms will continue into the night, although the severe threat for downburst winds will diminish a few hours after sunset.
The boundary left over from tonight’s storms will remain in the region tomorrow. This will keep the risk of a few isolated storms around for much of the region Wednesday. As a result, temperatures will drop a few degrees Wednesday, but it will still remain unseasonably hot and humid.
